This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 2000-383882, filed Dec. 18, 2000; and No. 2001-318368, filed Oct. 16, 2001, the entire contents of both of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a method for manufacturing a flat display element, and more particularly, to a method for manufacturing a flat display element in which two substrates are stuck on each other to form a display cell with a given gap between them.
2. Description of the Related Art
In recent years, flat display elements have widely been used as image display units of portable equipments for office automation, computer terminals, TV sets, etc. Usually, one such flat display element comprises a pair of electrode substrates opposed to each other across a given gap and an optical modulation layer, such as a liquid crystal, sealed between the electrode substrates. The respective peripheral edge portions of the electrode substrates are hermetically sealed with a sealant. A plurality of spacers for maintaining the fixed gap between the paired electrode substrates are arranged between the substrates.
These spacers are generally formed of a resin sphere each and are distributed at random in the display region of the electrode substrates. In a liquid crystal display device having a liquid crystal sealed in a display cell, therefore, the spacers disturb the orientation of liquid crystal molecules and the like, and their unbalanced distribution may possibly cause uneven display.
In order to obtain display images of higher quality levels, novel flat display elements have recently been developed and started to be used practically. In these flat display elements, spacer posts that are formed by patterning a photoresist or the like are arranged in non-display regions of the electrode substrates so that they serve to keep the gap between the substrates fixed.
The display cell used in one such flat display element is manufactured in the following steps. First, two mother glass plates each having a display cell forming region are prepared. A sealant and a dummy sealant are spread on the one mother glass plate so as to surround the forming region, and a tacker for preventing misalignment with the object mother glass plate is applied to end portions of the one mother glass plate.
Subsequently, the two mother glass plates are opposed to each other, and are roughly aligned by means of a plane mounter so that the shift of the pixel patterns that are opposed to one another in the display region of the flat display element is within about 5 xcexcm. Thereafter, the two mother glass plates are pressed and stuck on each other. Then, the mother glass plates are aligned with each other to lessen the shift of the pixel patterns. Thereafter, the tacker is cured to tack the two mother glass plates to each other, and moreover, the sealant and the dummy sealant are cured.
If the two mother glass plates are stuck on each other after they are aligned by means of the plane mounter, according to the manufacturing method described above, however, the tacker inevitably collapses, thereby causing the respective end portions of the mother glass plates to adhere to each other. In aligning the mother glass plates to lessen the pixel pattern shift by means of an aligner, therefore, the mother glass plates cannot be smoothly moved with respect to each other. Thus, the alignment takes a lot of time, so that the productivity lowers.
The present invention has been contrived in consideration of these circumstances, and its object is to provide a manufacturing method for a flat display element, in which alignment time is shortened so that productivity is improved.
In order to achieve the above object, according to an aspect of the present invention, there is provided a method for manufacturing a flat display element provided with a pair of substrates opposed to each other across a given gap and having the respective peripheral edge portions thereof stuck on each other with a sealant. This method comprises: preparing a pair of motherboards greater than the substrates; forming a display forming portion on each motherboard; locating the sealant on at least one of the motherboards so as to surround the peripheral edge portion of the display forming portion and locating, on the end portions of the motherboard, end spacers for maintaining the gap between the two motherboards and a tacker covering the end spacers; sticking the two motherboards on each other with the sealant, end spacers, and tacker between the two; aligning the two stuck motherboards with each other; tacking the two motherboards to each other by curing the tacker after the aligning; finally bonding the two motherboards to each other by curing the sealant after the tacking; and cutting the two motherboards outside the sealant after the final bonding so as to obtain the substrates.
According to another aspect of the invention, there is provided a method for manufacturing a flat display element comprising a pair of substrates opposed to each other across a given gap and including respective peripheral edge portions thereof stuck on each other with a sealant, a plurality of spacer posts provided between the substrates and maintaining the gap between the substrates, and an optical modulation layer sealed in a region surrounded by the sealant. This method comprises: preparing a pair of motherboards greater than the substrates; forming a display forming portion on each motherboard; locating the sealant on at least one of the motherboards so as to surround the peripheral edge portion of the display forming portion and locating, on end portions of the motherboard, end spacers for maintaining the gap between the two motherboards and a tacker covering the end spacers; sticking the two motherboards on each other with the sealant, end spacers, and tacker between the two; aligning the two stuck motherboards with each other; tacking the two motherboards to each other by curing the tacker after the aligning; finally bonding the two motherboards to each other by curing the sealant after the tacking; and cutting the two motherboards outside the sealant after the final bonding so as to obtain the substrates.
According to the methods for manufacturing a flat display element arranged in this manner, the respective end portions of the motherboards can be prevented from adhering to each other by means of the end spacers, so that the two motherboards can be smoothly moved with respect to each other during the alignment. Thus, the alignment time can be shortened, so that the flat display element can enjoy improved productivity.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.